Dan has pretty much answered the shipping question. The passage from Europe to Rangoon was in excess of 50 days. A ship arriving from Europe at the end of Sept 39 would have set sail in Aug 39 or earlier. The british would have had no reason to interfere with goods bound for China coming into Rangoon on a ship of a neutral country no matter what their origin. The Burma Road was open but it was so inefficiently run that there was a backlog of many months of supplies on the Rangoon docks awaiting shipment up the road to China.
The source of data in my earlier post is customs data for the Port of Rangoon.
With regard to hoarding there are many examples. One brief reference can be found in the comments of Vultee representative Warder in part 4 of this article.
http://www.wardirdforum.com/dunnp661.htm
RLD